Self-priming centrifugal pump



July 24, 1962 R. E. HUNTER SELFPRIMING CENTRIFUGAL PUMP 3 Sheets-Sheet 1Filed Oct. 26, 1959 ATTOENE VS July 24, 1962 R. E. HUNTER 3. 45.60

SELF-PRIMING CENTRIFUGAL PUMP Filed Oct. 26, 1959 3 Sheets-Sheet 2INVENTOR.

RICHARD E. HUNTER Kym,

July 24, 1962 R. E. HUNTER SELFPRIMING CENTRIFUGAL PUMP 5 Sheets-Sheet 3Filed Oct. 26, 1959 IN VEN TOR. RICH/1E0 E. HUNTER KQMZ ATrOe/VEYSUnited rates its Ohio

Filed Oct. 26, 1959, Ser. No. 848,804 2 Claims. (Cl. 103-113) Thisinvention relates to improvements in a self-priming centrifugal pump.

One of the objects of the present invention is to provide a self-primingcentrifugal pump designed and constructed to give positive primingaction without the use of an auxiliary vacuum pump, check valves, reeds,double v-olutes, siphon breakers and other auxiliary equipment whichhave heretofore been used to produce priming action in such a pump. Atthe same time, the improved pump herein disclosed gives optimumefliciency for centrifugal pumps of this nature after the completion ofthe priming cycle, which efficiency is decreased to a very slightdegree, if at all, because of the structure provided for theself-priming function.

The invention also provides a pump of the type described comprising acasing with an impeller chamber within the casing and a bladed impellerrotatably mounted in the chamber, with the walls of the chamber closelyassociated with the opposite faces of the impeller, there being aoutwater at one side of the chamber having substantially a running fitwith the impeller, the impeller chamber also having a partition wallwhich together with the side walls of the chamber provide a volutepassageway outside of the periphery of the impeller and extending morethan 360 degrees from the cutwater, this volute passageway progressivelyincreasing in cross sectional area from the outwater in the direction ofimpeller rotation at an uninterrupted rare at every point along itslength save for a priming passageway of small area communicatingdirectly between the lower part of the casing and the volute passagewayat a point in the latter passageway outside of the orbit of the impellerand more than 180 degrees from the cutwater in the direction of impellerrotation, this priming passageway being quite short and of venturiconstruction so that after the pump is primed, the priming passagewayconverts some of the velocity head of the pump liquid into pressure headgiving good pumping discharge in the reverse direction through thepriming passageway.

The invention further provides a low cost, simple construction in a pumpof this type.

Other objects and advantages of the invention will be apparent from theaccompanying drawings and description and the essential features thereofwill be set forth in the appended claims.

In the drawings,

FIG. 1 is a top plan view of a pump embodying this invention;

FIG. 2 is a sectional view of the same taken through the pump impellerand volute passageway along the line 2--2 of FIG. 3;

FIG. 3 is a central transverse sectional view of the pump of FIGS. 1 and2 taken along the line 33 of FIG. 1;

FIG. 4 is a sectional view taken along the line 44 of FIG. 3;

FIGS. 5 and 6 are fragmental sectional views taken along similarlynumbered lines in FIG. 2; while Fig. 7 is a view similar to FIG. 2 andshowing a modification.

In the pump shown in FIGS. 1 through 6', there is provided an outercasing 10 provided at the top with a filling plug 11 which is threadedinto a suitable opening. It should be understood that the sectionalconfiguration of the casing 10 as seen in FIGS. 2 and 4 may be generallysquare as there shown or generally circular, or arcuate at the bottom,or any other suitable shape so long as the principles of my inventionare carried out as hereinafter set forth. The casing 10 is generallycup-shape and open at one side as clearly seen in FIG. 3, which openside is closed by a face plate 12 which is connected to the casing 16 ina leak-proof manner as for instance by means of the O-ring seal 13. Athreaded handle screw 12 is utilized to hold the face plate to thecasing 10 in the position shown in FIGS. 1 and 3. The openings 10" inFIG. 4 are for self-sealing screws for holding the casing 1d rigid witha power source.

A conventional impeller 14 is mounted in the casing for rotation on ahorizontal axis although other arrangements will occur to those skilledin this art. The impeller comprises a back plate 14a having on one facethereof upstanding blades 14b which are conventional backward curvedvanes describing a tangential discharge angle of less than degrees. Theblades stop short of the center of the impeller and there provide anintake eye 15. The impeller is rigid with and driven by a shaft 16 whichextends out of the casing and is driven by a power source not shown. Itshould be understood that the bearings on the shaft 16 hold it inposition both radially and endwise and additional bearings might beprovided at the point 17 if desired or required. An annular flange 18integral with the casing 10 extends from the rear wall of the casingtoward the impeller and supports a seal 19 which prevents any leakagealong the shaft 16.

Means is provided for leading liquid to be pumped to the intake eye 15.This might take any one of various forms but is here shown as comprisinga manifold 20 which is formed integrally with the casing 10 and whichsurrounds an area axially opposite the eye 15 and leads therefromupwardly and toward the right as shown in FIG. 4 to an inlet conduit 21.

Means is provided defining an impeller chamber inside of the casing 10.This might be formed entirely supported by the casing 10 but in thepresent instance is supported partially by the face plate 12 andpartially by the casing 10 as best seen in FIG. 3. This impeller casinghas one side wall where the impeller back plate 14a has a running fitagainst the cover plate 12. The other side wall is formed by a wearplate 22 of annular shape secured to the manifold 20 by a plurality ofscrews 23 as clearly shown in FIG. 3. With a fully shrouded or closedimpeller, wear plate 22 is eliminated and the shroud has a close runningfit at this point and a wearing ring fit at the impeller eye area. Theradially outermost portion of the impeller chamber is completed by apartition wall 24 which in the present instance is integral with theface plate 12 but could be provided as an extension of the member 20 aswill be understood by those skilled in this art. This partition wallclosely approaches the orbit of the impeller at the point 25 to one sideof the impeller chamber to provide a cutwater there which issubstantially a running fit with the impeller. This partition wall 24together with the side Walls of the impeller chamber previouslydescribed together provide a volute passageway 26 which starts with analmost zero area at the point 25 and extends more than 360 degreestherefrom in the direction of impeller rotation finally terminating in adischarge opening 27. The area of this volute passageway progressivelyincreases in cross sectional area from the cutwater in the direction ofimpeller rotation at an uninterrupted rate at every point along itslength save for an entrance opening for a priming passageway to be laterdescribed. Such a true volute passageway greatly increases pumpingefi'iciency after priming has been accomplished and I believe this pumpto be a great advance over prior pumps spa-gees which utilized twogenerally parallel passageways of which the outer one acted as a primingpassageway with flow in one direction and later as a dischargepassageway with pumping in the opposite direction. At the point ofjunction of these two passageways in prior known pumps, there was asudden increase in the area of the volute passageway diminishing pumpingefficiency. It will be understood by those skilled in this art that thelength of the volute passageway 26 from the cutwater point 25 to thedischarge 27 is determined by well known laws and is of sufiicientlength to change a portion of the velocity head into pressure head togive good pumping action. The partition wall 24 has a radially inwardlyextending flange 24a integral therewith and of different radial extentdepending on the area of the volute passageway at the particular point.This flange 24a closely surrounds that portion of the manifold 20 whichsupports the wear plate 22 and is sealed against leakage at the meetingjoint by means of an O-ring seal 28 as clearly shown in FIG. 3.

A connection is provided in the upper portion of the casing 10 asindicated at 29 for the discharge of pumped liquid.

The pump as above described is designed for maximum pumping efficiencyand 1 will now describe the arrangement made so that the pump isself-priming without interfering except perhaps in a very slight degreewith such pumping efficiency.

Referring to FIG. 2, there is a priming opening provided at 30 directlyin the partition wall 24 and radially outside the orbit of the impeller14. I am aware that others have introduced priming liquid within theorbit of the rotating impeller but this causes undesirable turbulenceand reduces pumping efiiciency. I find that the efiiciency is wellmaintained if the cross sectional area at the level as shown in FIG. isapproximately equal to a circle whose diameter equals the width of theimpeller blades 14b when the dimension is measured between the sidewalls of the impeller chamber. The location of the opening 30 may bebetween 180 dagrees and 270 degrees from the cutwater 25 in thedirection of impeller rotation. However, the preferred location of theopening 30 is shown in FIG. 2 as having its center at that pointintersected by a line passing through the axis of the impeller and at anangle C of approximately 30 degrees counterclockwise from a verticalplane through the axis of the impeller. From the opening 30 a primingpassageway 31 extends outwardly from the impeller chamber. The directionof this passageway may vary somewhat from the position shown in FIG. 2but the best results are obtained when the axis of the primingpassageway is substantially vertical in that type of pump where the axisof rotation of the impeller is horizontal. I have shown such a centerline of the priming passageway in FIG. 2 wherein the angle D is 30degrees, thus making the center line of the priming passageway parallelto a vertical plane through the axis of the impeller.

The preferred form for the shape of the priming passageway is that of aventuri with its throat adjacent the opening 30 and with the length ofthe priming passageway being sufficient to convert enough velocity headto pressure head to give good discharge through the opening 30 duringthe pumping periods after the pump is primed. A preferred form for thewalls of the priming pasageway is that of a truncated cone although myinvention is not limited to such a shape. Referring to FIGS. 2, 5 and 6,if the cross section of the passageway at the level indicated by theline 55 is a circle diameter D1 and the area at the level of the line6-6 is that of a circle having the diameter D2, then the included angleB between the two sides of the truncated cone is preferred to be between6 and 8 degrees. Note that the circle of FIG. 2 designated by thediameter D2 extends to the dot-dash line X of FIG. 2 which is aprolongation of the shorter side or lefthand side as seen there of thewalls of the priming passageway. The length of the passageway,'designtaed L in FIG. 2, is such that the area at the diameter D2 isapproximately 1.49 times the area at the diameter D1 when the divergentangle B is 6 degrees, and the area at diameter D2 is approximately 1.63times the area at diameter D1 when the divergent angle B is 8 degrees.

The pump priming passageway would operate effectively even if the wallthereof seen at the left side in FIG. 2 were as long as the wall seen atthe right-hand side. However, I prefer to cut the left-hand wall backapproximately at an angle E of 30 degrees as shown in FIG. 2 so as toprovide an elliptical shape and a larger area at this opening whichallows a faster entrance of the priming liquid as well as giving abetter guidance to this liquid.

It will be understood by those skilled in this art that the location ofthe cutwater 25 is arrived at by means well known in the pump designindustry. The angle A in FIG. 2 is equal to the angle formed between theimpeller peripheral velocity and the absolute velocity on the impellerdischarge velocity diagram. Then, as shown in FIG. 2, the preferredlocation of the axis of the opening 30 is 240 degrees minus angle A in aclockwise direction (the direction of impeller rotation) from thecutwater 25.

The operation of this form of my invention should now be apparent. Thepump casing 10 is initially filled with liquid through the opening 11 atleast sufiiciently to give an initial pumping action. This would meanpreferably filled to at least the axis of the impeller and in any caseso as to cover the lower ends of the impeller blades. When the impellerstarts to rotate by means of its drive shaft 16 and in clockwisedirection as seen in FIG. 2., the impeller vanes 14b start dischargingliquid through the impeller chamber and through the discharge passageway26, 27 and into the separation and discharge chamber which is at theupper portion of the casing 10. There any lighter air or gas isseparated from the heavier water or liquid and discharged through theoutlet conduit 29. While this action is taking place, the heavier,substantially gas free, liquid is returned to the lower region of thepump casing 10 where it travels up through the priming passageway 31 tojoin the lighter gas laden liquid in the impeller or volute chamber 26.This cycle is repeated with a partial vacuum action taking place in theimpeller eye 15 which is there immediately filled with gas or air fromthe suction manifold 20 and the inlet conduit 21 until the suctionsystem is completely purged of gas or air. Once the pump is primed, asabove described, the venturi shaped passageway 31 acts as a dischargepassageway along with the normal volute discharge passageway 26, sincethe venturi section at passageway 31 is so designed as to convert partof the velocity energy in the impeller chamber to pressure energy at thepassageway 31. This action prevents any re-circulation 'with theresultant hydraulic efiiciency loss. The design of my pump is such thatduring the pumping period approximately percent of the discharge occursthrough passageway 26, 27 and approximately 25 percent throughpassageway 31.

The pump described is so designed as to allow for a sufficient volume ofliquid to be retained in the lower region of the casing 10 and in thesuction passageway to insure repeated priming even when high staticdischarge heads produce siphoning when the pump is shut down.

In the pump as modified in FIG. 7, all parts are identical except thatabout to be described and have, therefore, been given identicalreference characters. The difference between FIG. 7 and FIG. 2 residesin a bafile 32 provided at the bottom of the casing 10 and substantiallyin line with the passageway 31. The design of this baffle 32 is suchthat it will direct priming liquid in the direction of the full linearrows of FIG. 7 up into the priming passageway during the priming cycleof the pump. At the same time, the baflle preferably also serves tosmooth stream line flow of liquid out of the passageway 31 during thepumping cycle of the pump in the direction of the dotted line arrows.This refinement may be added if desired but the pump works very wellwithout it.

I have thus provided an improved centrifugal volute type pump which iscompletely self-priming in nature after the pump case has been initiallycharged with liquid to be pumped. This improved pump does not requirethe presence of any auxiliary priming devices. My improved pumpincorporates only a single volute passageway with the cross sectionalinterior area of this passageway, outside of the impeller, becomingprogressively larger in size from the tip or cutwater around to the exitthereof, not requiring a second or secondary cutwater tip whichheretofore has resulted in an area diiferentiation or an interruption inthe smooth progression of the volute passageway cross sectional areafrom cutwater to discharge. My improved pump gives fast, efficientpriming action even at the highest suction lifts, and with no sacrificein pumping efficiency due to recirculation of the liquid within the pumpitself after the priming has been completed. My improved pump, when onceprimed, becomes practically free of any plugging or fouling due to thepresence of foreign matter in the liquid to be pumped. Furthermore, thisimproved pump is inexpensive to build since only simple pattern and corework are required.

What is claimed is:

1. A self-priming centrifugal pump comprising a casing, means definingan impeller chamber in said casing, a bladed impeller rotatably mountedin said chamher and having an intake eye at its axis, a cutwater at oneside of said chamber and having substantially a running fit with saidimpeller, said impeller chamber defining means having side walls closelyassociated with opposite faces of said impeller, said chamber definingmeans also having a partition wall joined to said side walls and saidwalls providing a volute passageway outside of the periphery of saidimpeller and extending more than 360 degrees from said cutwater, saidvolute passageway progressively increasing in cross sectional area fromsaid cutwater in the direction of impeller rotation at an uninterruptedrate at every point along its length, the discharge end of said volutepassageway located in the upper part of said casing and opening towardthe top of said casing, there being a priming passageway communicatingdirectly between the lower part of said casing and said volutepassageway at a point in said volute passageway outside of the peripheryof said impeller and more than degrees from said cutwater in thedirection of impeller rotation, said priming passageway being of Venturishape with its throat adjacent said volute passageway, said primingpassageway having a flow area adjacent said volute passagewayapproximately equal to a circle whose diameter equals the width of saidimpeller blades between said side walls, means for liquid inlet to saidimpeller eye, and outlet means for discharging liquid from the upperpart of said casing, whereby substantially gas-free liquid enters saidpriming passageway during priming periods and liquid is discharged athigh efliciency from both said passageways during pumping periods, saidpriming passageway being delimited by walls approximately the shape of atruncated cone having a central axis substantially vertical, and saiddelimiting walls diverging outwardly into the lower part of said casingat an angle between approximately 6 to 8 degrees.

2. A pump as defined in claim 1 wherein said truncated cone has an outerend adjacent the bottom of said casing and an inner end adjacent saidimpeller and wherein the area at its outer end is between approximately1.49 and 1.63 times its area at its inner end.

References Cited in the file of this patent UNITED STATES PATENTS2,461,925 Rupp Feb. 15, 1949 2,627,817 Mann Feb. 10, 1953 2,755,743 RuppJuly 24, 1956 2,945,448 Frederick July 19, 1960 FOREIGN PATENTS 524,236Belgium Nov. 30, 1953 6 2 Gre rita M y 5

